Corn cobs have, for many years, added a certain measure of value to the harvest. Prior to the early 60's, the common corn harvesting practice was to pick the ears in the field, transport the crop to corn cribs, and later shell the corn off the cob at stationary shellers. The need to dispose of the cobs, after shelling, spurred most of the early research for useful cob end products. However, using stationary shellers limited the volume of cobs which had to be dealt with.
The advent of in-field shelling, by self-propelled combine harvesters created extreme efficiencies. The combine harvesters were designed to recover only shelled corn, or shelled corn incorporating only small amounts of cob, while crushing and discharging most of the cob back onto the ground. Early attempts to recover the cobs included adjusting the fingered vanes, on the harvester's chaffer, in order to open them wider and thus allow larger amounts of broken cob to fall through. However, this caused pieces of cob to lodge in the fingers and plug the chaffer. Accordingly, the vanes were lowered back to prevent plugging. Thus, only reduced volumes of cob residuals could be obtained for corn-and-cob-mix products.
In the late 70's and early 80's, it was found that a variety of high-moisture earcorn yielded even higher feed value for dairy and growing feed cattle than shelled corn itself. Certain feeds therefore included ground up cobs with kernels as a source of roughage. Corn cobs were also introduced into biomass procedures. In these instances, no attempt was made during threshing, or during other phases of combine operations, to preserve the cob in a useful shape.
Not long afterwards, cobs, which were fractured into segments having defined lengths of less than 3 inches, were found to have considerable use. The chunks were employed as a growth medium in mushroom cultures, as ornamental mulch, as non-harmful industrial abrasives and absorbents, as lightweight aggregates in the construction industry, as de-greasers, as water separators in alcohol production, and as clean burning non-sulfur fuel. Also, cob segments were produced as sources for chemicals such as the amino acids choline, and for oxalic acid and for xylitol, among others. In certain areas, cob segments were collected to extract the chemical solvent furfural.
In 1986, Chester McBroom was granted a patent on the Corn Cob Saver Sieve (U.S. Pat. No. 4,600,019). McBroom discovered an attachment, for combine harvesters, which enabled harvesting high-moisture earcorn type feed, etc. which incorporated higher percentages of cob. However, one drawback was the cobs could not be directly retrieved from the combine harvester.
Retrieval of cobs directly and automatically from the combine was nevertheless undertaken by Larry Shrawder beginning in 1989 (U.S. Pat. No. 4,892,505) and then in 1993 (U.S. Pat. No. 5,256,106). Therein, combine harvest separator arcs were modified to a circular shape, from elliptical; and, the cross bar spacing was altered on sieve slots; and a cob conveyor was added. But, his process and the special features of his combine design allowed harvesting only cobs having lengths which, as previously discussed, did not exceed 2-3 inches.
In 1999, Vernon L. Flame, in U.S. Pat. No. 5,941,768 entitled Corn Cob Collecting Apparatus For Use With Combines, dealt with the problem of harvesting dry corn cobs. He found that the cobs could not be separated from the stalks, husks, etc. through the use of air. Blowing air across the mix was too inefficient to separate cobs from MOGC. His solution was to use a wheeled apparatus connected to the rearward end of the combine in order to achieve separating the cobs.
In 2002, U.S. Pat. No. 6,358,141 by Stukenholtz disclosed an on-board system for separating whole corn cobs by modification to the sieve and straw walker system. However, the system does not provide the efficiency in separation needed to produce corn cobs at commercial demand levels.
In recent years, as the demand and utilization of fossil fuels has skyrocketed, likewise has the demand for corn cobs as alternative renewable energy sources and as feedstock for environmentally friendly biodegradable packaging. Enormous volumes of corn cobs are needed as a principal feed stock for ethanol fuels. One company plans on harvesting cobs from plots having a minimum of 4000 acres as a component of their system that will eventually handle harvesting as much as 275,000 acres of cobs by as early as 2011. The cobs will be used, inter alia, by public utility companies as biomass to co-fire with coal, because the cob's burn value is competitive with that of wood.
For projects of this size and volume, cobs will be stored outside. Since broken cobs would more readily mold, and decay than whole cobs, the goal currently is to harvest the cobs as whole, or in lengths as long as possible. The industry therefore needs no cobs less than 3 inches, and as many whole cobs as possible. If the cobs were broken up, they would require storage in a dry environment, and much greater cost.
A threshing and separating system for combine harvester that would significantly enhance the recovery and harvesting of corn cobs, particularly whole unbroken cobs, would constitute a welcomed but surprising advancement in the art.